Updates in Surgery (2022) 74:1985–1993 https://doi.org/10.1007/s13304-022-01341-2 ORIGINAL ARTICLE Kingsnorth's modified score as predictor of complications in open inguinal hernia repair Alejandro Bravo‑Salva1,2 · Margarita Salvá Puigserver2 · Clara Téllez‑Marqués1 · Marc Pérez‑Guitart1 · Alba González‑Martín3 · J. J. Sancho‑Insenser1,4 · M. Pera‑Roman1,2 · José A. Pereira‑Rodríguez1,2 Received: 24 March 2022 / Accepted: 19 July 2022 / Published online: 9 August 2022 © The Author(s) 2022 Abstract Purpose This study aims to analyse the postoperative complications (30 days) on unilateral primary inguinal hernia repair and prove their correlation with the preoperative modified scoring system of Kingsnorth (KN). Methods Prospective study design collecting data from patients who underwent surgery for unilateral primary inguinal hernia in a University Hospital. The data were collected in the National Inguinal Hernia Registry (EVEREG). A statistical analysis to assess the association between the presence of postoperative complications and the preoperative and intraopera‑ tive variables was performed. The patients were classified depending on their KN score. Surgical complications and their relationship with the classification were specifically analysed. Study design was performed following STROBE statements. Results The sample included 403 patients who met the inclusion criteria from which 62 (15.3%) subjects presented postop‑ erative complications. The variables that presented a statistically significant relationship with the appearance of complica‑ tions were a KN score of 5–8 (OR 2.7; 95% CI 1.07–4.82; P = 0.03) and the involvement of a member of the abdominal wall surgery unit in the procedure (OR 0.28; 95% CI 0.08–0.92; P = 0.03). The KN score correlated with a longer duration of surgery (Pearson's correlation 0.291; P < 0.0001). Conclusion The KN classification can predict the onset of surgical wound complications on patients who undergo a primary unilateral inguinal hernia surgery. A KN score of 5–8 has a higher probability of wound complications. When surgery is performed by the abdominal wall surgery unit, the chances of postoperative complications decrease. Keywords Unilateral inguinal hernia · Classification · Complications · Groin hernia repair · Hernia registries Introduction are the most frequent procedure and represent 75% of all abdominal wall hernias [2]. Abdominal wall hernias are one of the most frequent surgi‑ Throughout the history of surgery, numerous classifica‑ cal conditions. It is estimated that worldwide, around 20 tions of inguinal hernias have been proposed. The disad‑ million hernias are operated annually [1]. Inguinal hernias vantages of these classifications were that they were defined after surgery and complex. As a result, very simple ana‑ tomical localization systems were used (indirect, direct and * Alejandro Bravo‑Salva femoral), which are not useful to predict technical difficul‑ abravo@psmar.cat ties, complications or recurrences [3]. 1 Abdominal Wall Surgery Unit, Section of General Surgery, Currently, the European Hernia Society (EHS) has pro‑ Department of General Surgery, Parc de Salut Mar, Hospital posed a simpler classification system based on operative del Mar Medical Research Institute (IMIM), Passeig Maritim anatomy and hernia size [4]. This system could be useful 25‑29, 08003 Barcelona, Spain as a predictor, but it remains postoperative. It consists of 2 Department of Medicine and Life Sciences, Universitat a combination of letters and numbers according to hernia Pompeu Fabra, Barcelona, Spain characteristics. The letter indicates the position, assign‑ 3 Department of General Surgery, Hospital Comarcal del Alt ing the letter L to those in lateral position (indirect or Penedés, Barcelona, Spain external oblique hernias), the letter M to those medial 4 Surgery Department, Universitat Autónoma de Barcelona, to the inferior epigastric vessels (direct hernias) and the Barcelona, Spain 13 Vol.:(0123456789) 1986 Updates in Surgery (2022) 74:1985–1993 letter F to femoral hernias. The number corresponds to Methods the size of the hernial defect. If it is smaller than 1.5 cm it corresponds to number 1, between 1.5 and 3 cm it cor‑ This is a prospective, observational, single-center study of responds to number [2] and if it is larger than 3 cm it is patients operated for primary inguinal hernia at the Depart‑ classified as 3. Finally, if the hernia is primary it would ment of General Surgery of Hospital del Mar between 2019 then be classified as P and if it is recurrent as R [4]. and 2020. Study design was performed following STROBE In summary, there are many classification systems, but [7] statements. Hospital del Mar is one of the centres partici‑ they are heterogeneous and not very accurate to predict pating in the Spanish Abdominal Wall Registry (EVEREG) the evolution of the patient and the surgery [3]. [8]. Its main objective is to have a register of all surgical In 2004, Kingsnorth et al. designed a preoperative interventions related to the abdominal wall in Spain. Based classification system that considered hernia characteris‑ on this information, the aim is to analyse the results of the tics and scapular fold thickness [5] (Table 1). His work surgeries and assess the rate of complications associated showed that this system could predict the difficulty of with the surgery, as well as to evaluate the different surgical the surgical procedure. However, its correlation with the techniques and associated materials. development of postoperative complications and recur‑ Throughout the EVEREG National Inguinal Hernia Reg‑ rences has not been analysed. istry database, data related to patient demographics (age, A previous study performed at Hospital del Mar [6] weight, height, BMI, work activity, concomitant diseases, used a modification of this classification (KN) that previous personal history of abdominal wall pathology), and replaced scapular fold thickness (SF) with the patient's related to hernia characteristics (time of evolution, accompa‑ body mass index (BMI) (Table 1). nying symptoms, exploratory findings, classification accord‑ In this study [6], from a sample of 256 patients, it ing to modified Kingsnorth (KN) and EHS) were collected. was shown that scores greater than 5 required a longer Data regarding the surgical intervention, type of anaesthesia, operative time, but no significant relationship was dem‑ surgical findings, management of the nerves of the inguinal onstrated between the preoperative score and the com‑ region, operative time, intraoperative complications, days plication rate, probably due to the small sample size. of hospital stay and whether the intervention was performed Differences in recurrences were also not detected. We by a surgeon member of the Abdominal Wall Unit (AWU) hypothesized that the preoperative score could predict the were also recorded. development of postoperative complications in patients Inclusion criteria were: men aged > 18 years who under‑ operated for primary unilateral inguinal hernia in a larger went elective surgery for primary unilateral inguinal hernia sample of patients. and major outpatient surgery (MOS) or day surgery patients The aim of this study is to analyse the postoperative were also included. Exclusion criteria were recurrent her‑ complications (30 days) in patients undergoing primary nias, bilateral hernias and female sex. inguinal hernia repair surgery and to test their correlation Follow-up was performed by physical exploration at with the KN preoperative scoring system (Table 1). 4 weeks, 6 months and 12 months after surgery to detect The secondary aims are: to evaluate the correlation of complications, recurrence and/or chronic pain and if doubt KN score with recurrences and to study whether the com‑ abdominal ultrasound or computed tomography scan by bination of KN and postoperative (EHS) score increases specialized radiologist as required were performed. Com‑ the predictive capacity of complications. plications at 1 month were classified according to the Table 1  Original and modified Kingsnorth classification Hernia characteristics Patient characteristics original clas‑ Patient characteristics sification modified classification H1: Groin only; reduces spontaneously when lying down F1: SF < 15 mm F1: BMI < 25 H2: Groin only; reduces completely with gentle manual pressure F2: SF 15–24.9 mm F2: BMI 25–29,9 H3: Inguinoescrotal hernia reduces with manual manipulation F3: SF 25–34.9 mm F3: BMI 30–34.9 H4: Irreductible inguinoescrotal Hernia F4: SF > 35 mm F4: BMI > a 35 SF scapular fold thickness, BMI body mass index 13 Updates in Surgery (2022) 74:1985–1993 1987 Fig. 1  Flowchart. Hernias included in the study and follow-up at 1 month, 6 months and 1 year after the intervention Clavien–Dindo classification [9]. General complications were represented as mean and standard deviation (SD) or during hospital stay and surgical wound-related complica‑ median with interquartile range (IQR). Qualitative variables tions (SSO) at 1 month, such as hematoma, seroma and sur‑ were represented as proportions. The association between gical wound infection were analysed. qualitative variables was analysed using contingency tables Complications and recurrence were analysed according to (Chi-square) and the odds ratio (OR) was calculated. The the KN score classification (2–8 points) and the EHS score association between quantitative variables was analysed classification (1–6 points), obtaining a combined classifica‑ using Student’s t test for unpaired data. Statistical signifi‑ tion ranging from 3 to 14 points (KN-EHS classification). cance was established at P < 0.05. The sample size calculation was based on our previous Multivariate analysis was performed to identify risk fac‑ experience [6] due to previous incidence of complications. tors for the development of complications. The predictive capacity of each variable and its independence from the Statistical analysis other predictor variables were analysed using a binomial logistic regression model by sequentially entering the vari‑ The SPSS 25.0 program (IBM Inc. Rochester, MN, USA) ables with an input F of 0.5. was used for the statistical analysis. Quantitative variables 13 1988 Updates in Surgery (2022) 74:1985–1993 Approval was obtained from the Clinical Research Eth‑ Table 2  Patient demographics (N = 403) ics Committee (CEIC nº 2020/9578). The patients were Characteristics N (%) o median (IQR) informed, and the data were treated in accordance with Law 15/1999 on the Protection of Personal Data. The clinical trial Median age, years (IQR) 60 (50–72.1) protocol was registered under code NCT04806828 (Clini‑ Age > 70 years, N (%) 120 (29.8) calTrials.gov). BMI, median kg/m2 (IQR) 25.32 (23.5–27.7) Smoking history, N (%) 178 (44.0) Comorbidities, N (%) 173 (42.9) Results Diabetes mellitus, N (%) 43 (10.7) High blood pressure, N (%) 111 (27.5) From January 2019 to December 2020, a total of 434 Cardiac disease, N (%) 40 (9.9) patients met the inclusion criteria; 31 patients were excluded Pulmonary disease, N (%) 48 (11.9) due to lack of information on hernia classification, Fig. 1. Liver disease, N (%) 11(2.7) The demographic characteristics and pathological back‑ Renal disease, N (%) 14 (3.5) ground of the patients, as well as preoperative characteristics Stage IV renal disease, N (%) 1 (0.25) of the patients' hernias and their scores are shown in Table 2. Malignant neoplasia, N (%) 6 (1.5) Hernias with KN 5–8 constituted 15.7% of the population. ASA classification III/IV, N (%) 61 (15.1) Table 3 shows the variables related to the operation. The KN 2, N (%) 101 (25.0) mean operative time was 64 min. Most patients (61%) under‑ KN 3, N (%) 134 (33.5) went major outpatient surgery (MOS). Figure 2 displays the KN 4, N (%) 105 (26.0) analysis of the surgery duration related to the KN score. KN 5, N (%) 39 (9.7) Higher KN score correlated with longer duration of surgery KN 6, N (%) 20 (5.0) (Pearson correlation 0.291; P < 0.0001). KN 7, N (%) 4 (1.0) The overall complication rate (Table 3) was 15.4%, and KN 5–8, N (%) 63 (15.7) the SSO rate was 9.9%. 83% of the complications were clas‑ KN-EHS 3–8, N (%) 280 (92.7) sified as Clavien–Dindo I. KN-EHS 9–14, N (%) 22 (7.3) Analysis of complications according to KN score and QR interquartile range, BMI body mass index, ASA American Society KN-EHS score showed that KN5-8 scores had higher com‑ of Anesthesiologist, KN modified Kingsnorth score, KN-EHS King‑ plication rate in comparison with lower scores. The KN-EHS snorth score and EHS score addition score showed a similar distribution to the KN. When analysing the relationship of the study vari‑ ables with the presence of overall complications and SSO 0.07–0.82; P = 0.02) and KN score 2–4 points (HR 0.38; (Table 4), significant differences were observed, present‑ 95% CI 0.17–0.82; P = 0.01). ing lower overall complications and SSO if the intervention When analysing the composition of the cohort according was performed by an AWU surgeon. Significant results were to whether the operation was performed by a specialist sur‑ also obtained relating the KN5-8 score to the presence of geon (AWU) (Table 5), the AWU group had a significantly SSO. This result correlates with the results obtained in the higher percentage of patients aged over 70 years, higher obe‑ detailed analysis of complications. The relationship between sity rate and a higher frequency of KN score 5–8 patients. complications with the score is shown in Fig. 3. The sum of Primary analysis was performed in 382 patients due to 21 the two classification systems (KH-EHS 9–14) did not show patients did not perform 30-day postoperative outpatients statistically significant differences. clinical control. A total of 155 patients completed long-term In the binary logistic regression analysis, the fact that follow-up with a mean follow-up of 38.8 months. Lost of surgery was performed by a member of the AWU was pre‑ follow-up was mainly cause lack of outpatient clinic con‑ sented as a protective factor for complications (HR 0.38; trol, others due to pandemic situation physical exploration 95% CI 0.15–0.93; P = 0.035). When analyzing by the same was not possible. During follow-up, eight recurrences were method the incidence of SSO, two variables showed asso‑ diagnosed (5.1%). Univariate statistical analysis of recur‑ ciation with a lower frequency of complications: surgery rences demonstrated no significant differences related to performed by a member of the AWU (HR 0.24; 95% CI KN score (OR 0.65; 95% CI 0.08–5.5; P = 0.69), nor to the 13 Updates in Surgery (2022) 74:1985–1993 1989 Fig. 2  Operative time according to KN score operation performed by the AWU surgeon (OR 0.93; 95% The characteristics of the sample patients are similar to CI 0.88–0.98; P = 0.08). The only significant risk factor for those published in the literature [10]. Regarding the KN recurrences was a history of smoking (OR 8.91; 95% CI classification, 85% of the patients presented scores that were 1.07–74.22; P = 0.016). related to low surgical complexity. The variables related to the surgical procedure and its results were also comparable to those previously reported Discussion in other similar studies [8]. The operative time was shorter in patients with KN 2–4 without reaching statistically Inguinal hernia classification is expected to unify criteria to describe accurately the anatomy of the inguinal canal defect Table 3  Surgery-related variables [3, 4], and to provide a prediction model for outcomes after Variables N (%) surgery. Our study is the first in the literature to correlate the preoperative classification of inguinal hernias with the Duration, median, min, (IQR) 64 (50–76) development of complications and the duration of surgery. MOS, N (%) 246 (61.0) The sample size calculation based on our previous expe‑ Mean overall hospital stay, days (SD) 0.51 (1.0) rience [6] estimated a sampling of 630 patients. Due to the Average MOS hospital stay, days (SD) 0.08 (0.3) current situation caused by the COVID19 pandemic it has Operated by AWU surgeon, N (%) 85 (21.1) not been possible to reach the target as surgical activity has General complications, N (%) 62 (15.4) decreased for several months. Likewise, the operations dur‑ SSO, N (%) 40 (9.9) ing the year 2020 have been less complex, since priority was Hematoma, N (%) 22 (5.5) given to those that could be performed in a major outpatient Seroma, N (%) 14 (3.5) surgery (MOS) regime or day surgery to avoid the patient's Surgical wound infection, N (%) 5 (1.2) admission. All these factors have contributed to a lower per‑ Clavien–Dindo centage of patients with high scores than what was expected Grade 0, N (%) 341 (84.6) when designed. Grade I, N (%) 52 (12.9) Grade II, N (%) 9 (2.2) Grade IIIB, N (%) 1 (0.3) MOS major outpatient surgery, SSO surgical wound-related complica‑ tions, AWU​abdominal wall unit 13 1990 Updates in Surgery (2022) 74:1985–1993 Table 4  Univariate analysis Variable (N) General complications SSO of factors related to general complications and SSO N OR (95% IC) P N OR (95% IC) P Age > 70 years (120) 17 0.87 (0.48–1.6) 0.66 11 0.88 (0.43–1.83) 0.74 Diabetes mellitus (43) 10 1.8 (0.83–3.86) 0.13 7 1.92 (0.8–4.67) 0.14 ASA III/IV (61) 7 0.68 (0.29–1.57) 0.36 4 0.5 (0.21–1.74) 0.34 BMI > 30 (52) 11 1.58 (0.76–3.27) 0.21 7 1.49 (0.63–3.59 0.36 Smoking (178) 34 1.66 (0.96–2.86) 0.07 22 1.62 (0.84–3.13) 0.15 AWU surgeon (85) 6 0.36 (0.15–0.86) 0.02 3 0.28 (0.08–0.92) 0.03 KN 5–8 (63) 12 1.37 (0.68–2.74) 0.38 11 2.7 (1.07–4.82) 0.03 KN-EHS 9–14 (22) 4 1.33 (0.42–4.14) 0.62 4 2.61 (0.81–8.38) 0.10 ASA American Society of Anesthesiologists, BMI body mass index, AWU​ abdominal wall unit, KN modi‑ fied KN score, KN-EHS sum of modified KN and EHS score significant differences, most likely influenced by the sample manner, allowing a greater or lesser number of patients size. However, Pearson's correlation showed an association to be scheduled depending on their score. Approximately between KN score and operative time. This is very interest‑ each point of the KN classification correlates to 15 min of ing and has been previously reported [5, 6] and may be very surgery, which allows us to calculate the time for surgeries useful to distribute operating room time in a cost-effective between 30 and 120 min. Fig. 3  Graphical representation of the univariate analysis of the KN5-8 score and complications 13 Updates in Surgery (2022) 74:1985–1993 1991 A low proportion of patients presented complications, Table 5  Analysis of risk factors and complications for specialist most of them being mild (Grades I–II Clavien–Dindo [9]: abdominal wall surgeon (AWU) and non-specialist surgeon (non- AWU) 98.4% of all patients). Analysis of the variables related to postoperative complications failed to demonstrate a sig‑ Variables No AWU​ AWU​ P nificant association with the overall KN score. Instead, Mean age, years (SD) 59.7 (14.4) 61.8 (16.1) 0.21 wound-related complications showed a statistically sig‑ Age > 70 years, N (%) 87 (27.4) 33 (38.8) 0.04 nificant relationship with KN score 5–8 (P = 0.03), at the Mean BMI, kg/m2 (SD) 25.6 (3.3) 26.0 (3.8) 0.04 expense of an increase in postoperative seromas. This Smoking history, N (%) 144 (45.3) 34 (40.0) 0.38 confirms our initial hypothesis since wound complications Comorbidities, N (%) 131 (41.2) 42 (49.4) 0.17 are clearly influenced by the preoperative scoring system. Diabetes mellitus, N (%) 33 (10.4) 10(11.8) 0.71 This is important to provide more precise information to High blood pressure, N (%) 79 (24.8) 32 (37.6) 0.02 patients and to propose technical or therapeutic measures Cardiac disease, N (%) 29 (9.1) 11 (12.9) 0.29 to prevent their occurrence. Surgical wound infection was Pulmonary disease, N (%) 41 (12.9) 7 (8.2) 0.24 not related statistically significant, but there is a clear Liver disease, N (%) 7 (2.2) 4 (4.7) 0.21 trend towards a higher number of infections, which could Renal disease, N (%) 10 (3.1) 4 (4.7) 0.48 indicate the need for preoperative antibiotic prophylaxis in Stage IV renal disease, N (%) 1(0.3) 0 (0.0) 0.60 patients with KN5-8 regardless of their risk factors [11]. Malignant neoplasia, N (%) 3 (0.9) 3 (3.5) 0.08 The use of the summation of both scores (KN-EHS) ASA III/IV, N (%) 46 (14.5) 15 (17.6) 0.47 did not provide greater accuracy for the prediction of KN 5–8, N (%) 43 (13.5) 20 (23.5) 0.02 complications. KN-EHS 9–14, N (%) 13 (5.9) 9 (11.0) 0.13 An unexpected finding in our study was the statisti‑ Surgery duration, min (SD) 67.0 (19.8) 62.7 (29.8) 0.13 cally significant association of global and wound compli‑ Total complications, N (%) 56 (17.6) 6 (7.1) 0.02 cations with operations performed by surgeons who were SSO, N (%) 37 (11.6) 3 (3.5) 0.03 not members of the AWU. This is even more relevant if we Recurrences, N (%) 8 (7.0) 0 (0.0) 0.08 examine the comparison of patients operated on by each group of surgeons (Table 5). AWU patients apparently had BMI body mass index, ASA American Society of Anesthesiologist, more risks factors for complications: older age, higher KN modified Kingsnorth score, KN-EHS sum of modified KN and EHS score, SSO surgical wound-related complications BMI and a higher percentage of patients with KN score 5–8 (AWU 23.5% vs. Non-AWU 13.5%; P = 0.02). In con‑ trast, outcomes were better. This data suggest that inguinal assistant, were considered as AWU operations. It seems hernia operations, especially cases with KN score 5–8, that recurrences have a greater relationship with technique should be scheduled with surgeons specialized in abdomi‑ selection or operative events. nal wall surgery. Moreover, in the group classified as KN2- Subspecialisation in surgery has previously shown bet‑ 4, although statistical significance was not reached, there ter results in other studies such as in colorectal surgery was a clear trend towards a lower frequency of global (OR [14], oncology surgery [15]. Specifically in abdominal 0.43; 95% CI 0.16–1.12; P = 0.08) and wound complica‑ wall surgery, there are other studies on incisional hernia tions (OR 0.29; 95% CI 0.07–1.26; P = 0.08). Furthermore, repair, where also better results had already been detected it should be noticed that there were no wound infections in operations performed by a specialized surgeon [16]. or recurrence events in AWU-operated patients. Data shall Another factor that appeared to be associated with recur‑ be taken cautiously and confirmed with a prospective ran‑ rences was smoking history, both active and previous smok‑ domized control trial. ers. Smoking has been associated with a higher frequency Regarding hernia recurrence, the overall rate was 5.1%, of complications and recurrences in abdominal wall surgery in accordance with those previously reported [2, 12]. In previously [17–19]. In our study, it is remarkable that not this case, the KN score did not demonstrate any benefit. only active smoking had an influence on recurrences, but Moreover, most recurrences appeared in patients with a previous history of smoking addiction also had a nega‑ KN2-4 scores (87.5% of all recurrences). This has already tive impact on recurrences. This also deserves a prospective been pointed out by other authors who detected that the study with a larger sample size with patients without active frequency of recurrence in low complexity hernias was smoking, but with a history of tobacco addiction to ensure a higher [13]. Likewise, it is noteworthy that there was no correct correlation with groin hernia recurrence. recurrence when the surgery was performed by an AWU The main strengths of this study are its prospective nature surgeon. It should be taken into account that all operations and the fact that data were collected in a unified national in which a specialized surgeon was present, as surgeon or registry of inguinal hernia. 13 1992 Updates in Surgery (2022) 74:1985–1993 Weaknesses relate to the decreased sample size due to References the current COVID-19 pandemic situation and the large amount of loss to follow-up due to cancellation of appoint‑ 1. Kingsnorth A, LeBlanc K (2003) Hernias: inguinal and incisional. ments for this same reason, so that only 44.2% of patients Lancet 362(9395):1561–1571. https://​doi.​org/​10.​1016/​S0140-​ 6736(03)​14746-0 were followed long-term. 2. Hammoud M, Gerken J. Inguinal Hernia. In: StatPearls [Internet] In conclusion, the KN classification allows predict‑ 2020 [Consultado 29 Mar 2021]. Available from: https://​www.​ ing the occurrence of operative wound complications in ncbi.​nlm.​nih.​gov/​books/​NBK51​3332/ patients operated on for unilateral primary inguinal hernia. 3. Zollinger R (2003) Classification systems for groin hernias. Surg Clin North Am 83(5):1053–1063. https://​doi.​org/​10.​1016/​S0039-​ KN score 5–8 has higher chances of wound complications. 6109(03)​00126-9 When surgery is performed by a specialist in abdominal 4. Miserez M, Alexandre JH, Campanelli G, Corcione F, Cuccu‑ wall surgery, chances of postoperative complication are rullo D, Pascual MH et al (2007) The European hernia society lower. groin hernia classification: simple and easy to remember. Hernia 11(2):113. https://​doi.​org/​10.​1007/​s10029-​020-​02212-8 5. Kingsnorth A. A clinical classification for patients with inguinal hernia. Hernia. 2004;8(3). https://​doi.​org/​10.​1007/​ Author contributions MPS, ABS and JPR were major contributors to s10029-​004-​0228-3 writing the manuscript, and they contributed equally to this work, all 6. Dorcaratto, D., Pereira, J., Climent, M., Junca, V., Segura, M. authors were involved in the design of the study and drafting the manu‑ and Grande, L. Kingsnorth difficulty score for the classification script; JPR, ABS, MPS, CTM, MPG, AGM collected and analyzed of inguinal hernia. A way to optimize surgical planning. Hernia. data, MPR and JSI critically revised the manuscript till the final version 2010; 14(Suppl 1), p.S50. was reached. All the authors read and approved the final manuscript. 7. Pereira J, López-Cano M, Hernández-Granados P, Feliu X (2016) Initial Results of the National Registry of Incisional Hernia. Cir Funding Open Access funding provided thanks to the CRUE-CSIC Española (English Edition) 94(10):595–602. https://​doi.​org/​10.​ agreement with Springer Nature. No funds or grants were obtained to 1016/j.​cireng.​2016.​09.​014 conduct the study. 8. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Van‑ denbroucke JP (2007) Strengthening the Reporting of Observa‑ Availability of data and material The datasets generated during and/or tional Studies in Epidemiology (STROBE) statement: guidelines analysed during the current study are available from the corresponding for reporting observational studies. BMJ 335(7624):806–808. author on reasonable request. https://​doi.​org/​10.​1136/​bmj.​39335.​541782.​AD 9. Dindo D, Demartines N, Clavien PA (2004) Classification of sur‑ gical complications: a new proposal with evaluation in a cohort of Declarations 6336 patients and results of a survey. Ann Surg 240(2):205–213. https://​doi.​org/​10.​1097/​01.​sla.​00001​33083.​54934.​ae Conflict of interest None of the authors declare conflict of interests 10. Bay-Nielsen M, Kehlet H, Strand L, Malmstrøm J, Andersen within the study issue. FH, Wara P et al (2001) Quality assessment of 26,304 hernior‑ rhaphies in Denmark: a prospective nationwide study. Lancet Consent to participate Informed consent was obtained from all indi‑ 358(9288):1124–1128. https://​doi.​org/​10.​1016/​s0140-​6736(01)​ vidual participants included in the study. 06251-1 11. Sánchez J, Seco L, García J (2001) Antibiotic prophylaxis and her‑ Ethical requirements. Ethical hospital committee approval was nia repair. Systematic quantitative review results. Enferm Infecc obtained to perform study’s prospective data collection. Microbiol Clin 19(3):107–113. https://d​ oi.o​ rg/1​ 0.1​ 002/1​ 46518​ 58.​ cd003​769.​pub4 Trial registration number NCT04806828 (clinicaltrial.gov). Date of 12. Simons MP, Smietanski M, The HerniaSurge Group et al (2018) registration, March 19, 2020. International guidelines for groin hernia management. Hernia 22:1–165. https://​doi.​org/​10.​1007/​s10029-​017-​1668-x 13. Burcharth J (2014) The epidemiology and risk factors for recur‑ Open Access This article is licensed under a Creative Commons Attri‑ rence after inguinal hernia surgery. Dan Med J 61(5):B4846 bution 4.0 International License, which permits use, sharing, adapta‑ 14. Borowski DW, Kelly SB, Bradburn DM, Wilson RG, Gunn A, tion, distribution and reproduction in any medium or format, as long Ratcliffe AA, the members of the Northern Region Colorectal as you give appropriate credit to the original author(s) and the source, Cancer Audit Group (2007) Impact of surgeon volume and spe‑ provide a link to the Creative Commons licence, and indicate if changes cialization on short-term outcomes in colorectal cancer surgery. were made. The images or other third party material in this article are Br J Surg 94:880–889. https://​doi.​org/​10.​1002/​bjs.​5721 included in the article's Creative Commons licence, unless indicated 15. Bilimoria KY, Phillips JD, Rock CE et al (2009) Effect of surgeon otherwise in a credit line to the material. If material is not included in training, specialization, and experience on outcomes for cancer the article's Creative Commons licence and your intended use is not surgery: a systematic review of the literature. Ann Surg Oncol permitted by statutory regulation or exceeds the permitted use, you will 16:1799–1808. https://​doi.​org/​10.​1245/​s10434-​009-​0467-8 need to obtain permission directly from the copyright holder. To view a 16. Pereira JA, Bravo-Salva A, Montcusí B, Pérez-Farre S, Fresno de copy of this licence, visit http://​creat​iveco​mmons.​org/​licen​ses/​by/4.​0/. Prado L, López-Cano M (2019) Incisional hernia recurrence after open elective repair: expertise in abdominal wall surgery matters. BMC Surg 7:19–103. https://d​ oi.o​ rg/1​ 0.1​ 186/s​ 12893-​019-​0569-6 13 Updates in Surgery (2022) 74:1985–1993 1993 17. Lindström D, Sadr Azodi O, Bellocco R, Wladis A, Linder S, 19. Ooms LS, Verhelst J, Jeekel J, Ijzermans JN, Lange JF, Terkivatan Adami J (2007) The effect of tobacco consumption and body T (2016) Incidence, risk factors, and treatment of incisional her‑ mass index on complications and hospital stay after inguinal nia after kidney transplantation: an analysis of 1,564 consecutive hernia surgery. Hernia 11(2):117–123. https://​doi.​org/​10.​1007/​ patients. Surgery 159(5):1407–1411 s10029-​006-​0173-4 18. Sørensen LT, Hemmingsen UB, Kirkeby LT, Kallehave F, Jør‑ Publisher's Note Springer Nature remains neutral with regard to gensen LN (2005) smoking is a risk factor for incisional hernia. jurisdictional claims in published maps and institutional affiliations. Arch Surg 140(2):119–123. https://​doi.​org/​10.​1001/​archs​urg.​ 140.2.​119 13